Debian Jigdo mini-HOWTO

Getting Debian ISOs has always been a painful, slow and supremely inefficient process.
Jigdo is a tool for distributing and obtaining Debian ISOs in an easy, fast and very efficient
manner. This HOWTO describes why you should use jigdo, a little bit about how it works and how
you use it to get and update Debian ISOs.

Jigdo is a very general tool, and isn't tied specifically to Debian ISOs. The jigdo tools
can be used to make any ISO available for download in the same easy, fast and efficient manner
they're used for Debian ISOs. This HOWTO will cover this as well, but we'll focus primarily on
downloading Debian ISOs.

1. Administrata

1.1. Authorship and Copyright

This document is copyright (c) 2001 Peter Jay Salzman, <p@dirac.orgZZZ>. Permission is granted to copy,
distribute and/or modify this document under the terms of the Open Software License (OSL),
version 1.1. I hate HOWTO's that include the license; it's a tree killer. You can read the
OSL at http://opensource.org/licenses/osl-1.1.txt.

If you want to create a derivative work or publish this HOWTO for commercial purposes,
I'd appreciate it if you contact me first. This will give me a chance to give you the most
recent version. I'd also appreciate either a copy of whatever it is you're doing or a
spinach, garlic, mushroom, feta cheese and artichoke heart pizza.

1.2. Acknowledgements

I would like to thank the author of jigdo, Richard Atterer, simply for writing jigdo. Anyone who
has obtained Debian ISOs by other means will know why. This HOWTO started out as some
webpages I wrote about my experience with jigdo. Richard took the time to email me extensive
corrections, clarifications and answers to questions I had about jigdo. Since then, he has
read my work many times. Richard is a developer who not only cares about his work, but also
about the people who use it. Sadly, this is becoming less common in this busy world we live
in. Thanks, Richard!

I'd also like to thank
Conrad Wood,
Elcio Mello,
Marcelo Ramos,
Yufeng Wang,
Tsukasa Yamaguchi,
Yuri Kozlov, and
Oguz Yarimtepe
for translating this mini-HOWTO into languages other than English. I feel totally honored
that they have found my words worthy of their time and effort. Thanks, guys!

1.3. Comments and Corrections

I care a great deal about the people who use this document. Even mini-HOWTOs take a
long time to write, and I wouldn't have invested so much effort into something people don't
understand. If you have comments, corrections or suggestions, even in matters like writing
style, don't hesitate to email me. As long as I'm not totally swamped by my PhD
dissertation and the book I'm writing on debugging code with GDB/DDD for No Starch Press, I'll
do my best to respond to each email I receive about this mini-HOWTO. News flash: I've
completed my Ph.D.; now I'm swamped with job hunting. Does anyone need to hire a theoretical
physicist?

2. Why jigdo?

2.1. How Does One Get A Debian ISO Image Set?

If you want a set of Debian CDs there are many ways of getting them. One way is to buy
them from vendors who sell Debian CDs.
This definitely has merit since some of the vendors donate money back to the Debian project.
Your donations help make sure that Debian is around for a long time.

Another way of getting a set of Debian CDs is to burn your own set. This first entails
obtaining an ISO image and then burning that ISO image to a blank CD. Before jigdo, there
were two ways of creating Debian CDs:

Downloading the entire ISO

Using the pseudo-image kit (PIK)

This document is about the newer and better way of obtaining Debian ISO images, using a
tool called jigdo. In fact, the PIK is now officially dead and all further references to it
have been removed from this document. The canonical method of getting Debian ISO images is
with jigdo.

2.2. Why Not Download The Whole ISO Image?

There are mirrors which offer http and ftp downloads of Debian ISOs. The problem is
that there are very few mirror sites, and their bandwidth can't support everyone who wants
Debian ISOs. For example, fsn.hu has reportedly saturated the connection of its provider.
The outgoing traffic reaches a few terabytes per month!

In addition, Debian testing and unstable get updated often. Your ISOs may become
outdated the same day you download them unless you find some sneaky way of updating them like
mounting the ISO on a loopback device and using rsync (which is what the PIK did). So if you
want up-to-date ISO images, you must download a new set of ISO images every day. Clearly,
this is not the way you want to obtain Debian ISOs!

Even if you want to download the stable ISO images, they still get updated every few
months. Downloading the ISO images will give you up-to-date images for a few months, but
every time a new revision of Debian stable is released, you'll need to go through the painful
process of downloading the entire ISO set from scratch. This is not a good use of your time
and the mirror's resources.

2.3. What Is Jigdo?

Jigdo (which stands for "Jigsaw Download") was written by Richard Atterer and is released under the GNU GPL.
It's a tool that allows efficient downloading and updating of an ISO image. Any ISO image.
Jigdo is not Debian specific, however Debian has chosen it to be the official method of
downloading ISO images.

A common misconception is that jigdo creates ISO images; it doesn't. Let's discuss the
overall process of how jigdo allows you to obtain an ISO image. Let Adam (a Debian release
manager) be the person offering the ISO image. Let Betty (a Debian user) be the person who
wants to download the ISO image.

Adam first creates an ISO image suitable for burning a CD. He might use a utility
like mkisofs or debian-cd to create
the ISO image. He also creates two small files associated with his newly created image: a
.jigdo file and a .template file. He makes these
two files available for download to anyone who wants to obtain his ISO image.

Betty then downloads the .jigdo and
.template files. She uses jigdo-lite along
with these two files to download Adam's ISO image.

When Debian gets updated, Adam creates a new version of the ISO and generates new
.jigdo and .template files.

When Betty wants to update her CDs, she downloads the new .jigdo
and .template files and uses them with
jigdo-light to update her copy of the ISO images. The important
thing here is that she only downloads the differences between her old ISO and Adam's new
ISO. She does not have to re-download the parts that are unchanged.

Jigdo comes with two utilities: jigdo-file (used by Adam)
which creates the .jigdo and .template files, and
jigdo-lite (used by Betty) which uses these two files to download
or update the ISO. If all you want to do is obtain/update Debian ISOs, you'll only use
jigdo-lite. You can forget that jigdo-file even exists.
:-)

Jigdo addresses all the problems with the other methods of obtaining Debian ISO
images:

It's much faster than downloading the entire ISO image.

Unlike downloading the entire ISO image, it can take an outdated CD (or a loop
mounted outdated ISO image), download only the files that have changed
since the CD (or ISO image) was created and create a new updated ISO. Very similar to how you
use cvs to update source code.

jigdo-lite uses wget which, by default, uses http to transfer files. Unlike
rsync, http is never blocked by firewalls (except the ones behind which you shouldn't be using
jigdo to begin with).

Jigdo is very kind to the bandwidth of the servers offering the Debian images.
The Debian mirrors can handle a bigger load of people using jigdo to download Debian images
than with other methods of getting them.

Clearly, jigdo is the best method of obtaining Debian ISO images.

3. How Jigdo Works (optional)

You don't need to know this material to download Debian ISOs, but it may help demystify how
jigdo works. If you're not interested in the details, simply fast forward to Section 4, "How Do I Use Jigdo".

3.1. Preparing The ISO For Download

A CD image is a filesystem called iso9660, but for this discussion, we can safely talk
about a CD image as being a big file called an "ISO image" (about 650MB) that contains files
at various offsets. For instance, if a CD contains a 567 byte file named README, the ISO
image might contain the README file's contents between offsets 20480000 and 20480567. You can
visualize a CD image as:

jigdo-file takes two things as input: the complete CD image
(so the ISO already needs to have been made) and a set of files which may or may not be in the
image. Here's a visualization of jigdo-file's input:

jigdo-file found that the files file-0, file-1
and file-3 were contained in the ISO image. It removed the contents of
the these files and replaced them with each file's md5 checksum (the
md5-0, md5-1, etc).

The "x" data (directory information, zero padding, etc)
within the ISO image is compressed and written to the .template file. Finally, any files
within the ISO image that weren't supplied as loose files (like file-2)
are also compressed and written to the .template file. This is shown as "c" data in the .template file visualization.

Loose files which were supplied to jigdo-file that aren't
found in the ISO image (like file-4) are ignored.

3.3. The .jigdo File

Given an input of an ISO image and a set of loose files which may or may not be in the
ISO image, jigdo-file outputs a .jigdo file for that ISO image. The Debian .jigdo files are
gzipped, so you need to use zcat or zless to view them. Here's what a .jigdo file looks like
when you gunzip it:

The .jigdo file simply provides a mapping between the md5sum of a file within the ISO
image and the download URL of that file. There are some other things within the
.jigdo file,
and if you look through it, you'll see the .jigdo file has the same
format as a ".ini" file. It should be self explanatory, but if you want the nitty-gritty
details, see the jigdo documentation.

The format shown above is not quite what you'd see in a typical .jigdo file, but it's
very similar. If you look at the [Servers] section at the bottom of the .jigdo file, you'll
see exactly what the difference is between what I showed above and an actual
.jigdo file.

3.4. Downloading The Image

Once you use jigdo-file to generate a
.jigdo and .template file for an ISO image, anyone
can use jigdo-lite to download that image. jigdo-lite downloads
all the files of a Debian ISO using wget, assembles them and forms
a copy of the original ISO image on the fly.

4. Downloading Your First Image (In 5 Easy Steps)

We'll assume that you're starting from scratch and don't have any Debian ISOs on hand. Once
you burn your set of ISOs, you can use jigdo-lite later to update them. We'll cover updating your
ISOs in the next section.

4.2. Download The .template And .jigdo Files

For each ISO image you want to download, you'll need both the .jigdo and .template file
for that image. Both files follow the same naming convention:

distro-arch-n.jigdo
distro-arch-n.template

where distro is the name of the distro (like "sarge"), arch is the architecture (like
"i386") and n is the disk number (like "1").

For example, sarge has 8 images, so you need to download 8 .jigdo files and 8 .template
files. They can be downloaded from http://www.debian.org/CD/jigdo-cd/. The first .jigdo and .template file are named
sarge-i386-1.jigdo and sarge-i386-1.template
respectively.

4.3. Run jigdo-lite

Run jigdo-lite and give it the .jigdo
file of the image you want to download. Using Sarge as an example:

lucifer$ ls
sarge-i386-1.jigdo sarge-i386-1.template
lucifer$ jigdo-lite sarge-i386-1.jigdo
Jigsaw Download "lite"
Copyright 2001-2003 by Richard Atterer <jigdo@atterer.net>
Getting mirror information from /etc/apt/sources.list
-----------------------------------------------------------------
Images offered by `sarge-i386-1.jigdo':
1: 'Debian GNU/Linux testing "Sarge"
- Official Snapshot i386 Binary-1 CD' (sarge-i386-1.iso)
Further information about `sarge-i386-1.iso':
Generated on Fri, 7 Feb 2003 20:31:28 -0700
-----------------------------------------------------------------
If you already have a previous version of the CD you are
downloading, jigdo can re-use files on the old CD that are also
present in the new image, and you do not need to download them
again. Mount the old CD ROM and enter the path it is mounted under
(e.g. `/mnt/cdrom').
Alternatively, just press enter if you want to start downloading
the remaining files.
Files to scan:

If you suspended jigdo-lite with control+z
(don't do this; I'll tell you what you'd see) and looked at the output of
ls, you'd find a new file in the directory named
sarge-i386-1.jigdo.unpacked. It turns out that .jigdo files are gzip'ed.
This file is simply a gunzip'ed version of the .jigdo file.

Right now, jigdo-lite is telling us that if we have an
outdated version of first CD of sarge, we should give the pathname to the CD. This is how you
update your ISO images (or complete your incomplete downloads). Since we're assuming that
you're starting from scratch and have no Debian ISOs yet, we have nothing to scan. We'll
cover this in Section 5, so just press ENTER.

4.4. Specify A Mirror

You'll see:

-----------------------------------------------------------------
The jigdo file refers to files stored on Debian mirrors. Please
choose a Debian mirror as follows: Either enter a complete URL
pointing to a mirror (in the form
`ftp://ftp.debian.org/debian/'), or enter any regular expression
for searching through the list of mirrors: Try a two-letter
country code such as `de', or a country name like `United
States', or a server name like `sunsite'.
Debian mirror [http://linux.csua.berkeley.edu/debian/]:

By default, jigdo-lite pulls the mirror from your
/etc/apt/sources.list. If you want to use a different mirror, you would
specify a different mirror here. If this is the mirror you want to use, press
ENTER. Jigdo-lite will then write a .jigdo-lite file in
your home directory.

Next, if the .jigdo file you're using references a package which
needs to be downloaded from a Non-US server, jigdo-lite will prompt
you for a Debian Non-US mirror. The message displayed (and your response) will be very
similar to the mirror dialog in the previous paragraph.

-----------------------------------------------------------------
The jigdo file also refers to the Non-US section of the Debian
archive. Please repeat the mirror selection for Non-US. Do not
simply copy the URL you entered above; this does not work because
the path on the servers differs!
Debian non-US mirror [http://linux.csua.berkeley.edu/debian-non-US//]:

Jigdo-lite will write your choice to ~/.jigdo-lite. However, if
the image you're about to download doesn't contain Non-US software you won't see this
dialog.

If you want to change the default mirrors you use with jigdo at any time in the future,
you can modify these two lines in ~/.jigdo-lite:

There'll be a lot of messages flying across your screen; if this is confusing to you,
see Section 6.13. While jigdo-lite is downloading the packages, switch to
another console (or open another xterm) and do an ls in the directory
you're running jigdo-lite in. Now there should be 6 files in the directory:

sarge-i386-1.iso.list

sarge-i386-1.iso.tmp

jigdo-file-cache.db

sarge-i386-1.iso.tmpdir/

sarge-i386-1.jigdo

sarge-i386-1.jigdo.unpacked

sarge-i386-1.template

The sarge-i386-1.iso.tmpdir/ directory contains
all the Debian packages that jigdo-lite downloads. Every so often,
the directory gets flushed and the files get written to
sarge-i386-1.iso.tmp, which is an temporarily incomplete version of the
ISO image you want. Note that sarge-i386-1.iso.tmp won't appear until
the first time sarge-i386-1.iso.tmpdir/ gets
flushed.

jigdo-file-cache.db is a Berekeley DB file containing md5sums of
any files read in when you specify a directory at the Files to scan:
prompt. It's described in Section 7.3.

At this point, go play some Quake III because this will take some time (you may want to
play on a different machine because jigdo is very disk intensive when it flushes files to the
.iso.tmp file). At some point, the download will finish and you'll be
staring at:

FINISHED --13:32:58--
Downloaded: 7,469,872 bytes in 9 files
Found 9 of the 9 files required by the template
Successfully created `sarge-i386-3.raw'
-----------------------------------------------------------------
Finished!
The fact that you got this far is a strong indication that `sarge-i386-3.raw'
was generated correctly. I will perform an additional, final check,
which you can interrupt safely with Ctrl-C if you do not want to wait.
OK: Checksums match, image is good!

5. Updating Your Image

Presumably, you've read the last section, followed the instructions, burned your newly
created ISO files onto CD and are feeling warm and fuzzy. Sooner or later, some packages will get
updated and now you want to donate your old CDs to some newbie at your local LUG's installfest and
burn yourself a set of updated CDs. Since you're well on the way to becoming a jigdo-guru, we
won't go into as much painful detail as we did in the last section.

The first step is to download the .jigdo and .template files, again, for the images you want
to update. You may wonder why you need to download them a second time. The reason is because the
updated image you want to download has changed. Files may have been added or deleted, but even if
not, any updated packages or files will have a different checksum from the checksum listed in the
.jigdo and .template files you used when you first downloaded the images.

At this point, you're either holding an outdated Debian CD in your hand or you have the CD's
outdated ISO image on your hard drive. Let's go through the steps of getting an updated ISO file.
If you have a CD, put it in your CD drive and mount it:

$ mount /cdrom

On the other hand, if you have an ISO file you'd like to update, mount it as a loop device
(you may need to be root to do this). Using Woody as an example:

# mount -o loop woody-i386-1.iso /mnt

Now run jigdo-lite with the .jigdo file as
an argument.

$ jigdo-lite woody-i386-1.jigdo
-----------------------------------------------------------------
Jigsaw Download "lite"
Copyright 2001-2002 by Richard Atterer <jigdo@atterer.net>
Loading settings from `/home/p/.jigdo-lite'
-----------------------------------------------------------------
Images offered by `woody-i386-1.jigdo':
1: Debian GNU/Linux 3.0 r0 Woody
- Official i386 Binary-1 CD (debian-30r0-i386-binary-1.iso)
Further information about `debian-30r0-i386-binary-1.iso':
Generated on Thu, 18 Jul 2002 14:34:12 +0100
-----------------------------------------------------------------
If you already have a previous version of the CD you are
downloading, jigdo can re-use files on the old CD that are also
present on the new image, and you do not need to download them
again. You found the secret message; you're a very careful
reader. Mount the old CD ROM and enter the path it is mounted
under (e.g. `/mnt/cdrom'). Alternatively, just press enter if you
want to start the download of any remaining files.
You can also enter a single digit from the list below to
select the respective entry for scanning:
1: /mnt
Files to scan:

jigdo-lite is asking us to give it the location of your mounted CD (if you're updating a CD)
or your loop mounted ISO file (if you're using the ISO file). I'm using an ISO file loop mounted
on /mnt, so I'll enter /mnt. If you're updating a CD, enter the mount directory of your CD,
which is most likely /cdrom. In either case,
jigdo-lite will scan the directory of your mounted media, determine
which files need updating and re-use the files which don't need updating. See also Section 7.2, "More About Scan Sources".

What happened? Actually, I wanted to show you this because you'll bump into it sooner or
later. I'm updating an ISO file, but the outdated image file is in the same directory I'm working
in. Jigdo-lite wants to generate a file called woody-i386-1.iso but there's
already a file by that name in the current directory (the outdated image). Jigdo-lite doesn't
want to destroy that file, so it bails and lets me know that I can either delete that file or use
--force to overwrite the file. You could also rename or move the file too,
but I guess jigdo-lite assumes we already know this. :-)

Don't be timid about moving or renaming the image file just because it's loop mounted. The
filesystem uses inodes under the hood, and even if you move or rename the file, the inode stays
the same. You won't hurt the filesystem mounted under /mnt.
As for deleting the ISO file, that won't hurt the mounted filesystem either. A file's inode gets
deallocated only when the inode's reference count drops to zero. Mounting the ISO image bumps the
reference count up, so the file really gets deleted only after you rm the file
and umount the loop device. All you people who are updating the CD don't
have to worry about any of this. :-)

$ jigdo-lite woody-i386-1.jigdo
-----------------------------------------------------------------
Jigsaw Download "lite"
Copyright 2001-2002 by Richard Atterer <jigdo@atterer.net>
Loading settings from `/home/p/.jigdo-lite'
-----------------------------------------------------------------
Images offered by `woody-i386-1.jigdo':
1: Debian GNU/Linux 3.0 r0 Woody - Official i386 Binary-1 CD
(debian-30r0-i386-binary-1.iso)
Further information about `debian-30r0-i386-binary-1.iso':
Generated on Thu, 18 Jul 2002 14:34:12 +0100
-----------------------------------------------------------------
If you already have a previous version of the image you are
downloading, jigdo can re-use files on the old image that are also
present on the new image, and you do not need to download them
again. Mount the old CD ROM and enter the path it is mounted under
(e.g. `/mnt/cdrom'). Alternatively, just press enter if you want
to start the download of any remaining files.
You can also enter a single digit from the list below to
select the respective entry for scanning:
1: /mnt
Files to scan: /mnt
Not downloading .template file - `woody-i386-1.template' already present
...
Found 1200 of the 1224 files required by the template
...

jigdo-lite remembers that I wanted to scan /mnt and
tells me I can either type 1 to scan that directory or type the directory in
again. Since I'm a perverse person, I type the name of the directory again.

The ellipsis represent some text that changes rapidly. The first ellipsis is a dynamic list
of what files jigdo-lite is scanning. The second ellipses denotes progress in writing
woody-i386-1.iso.tmp. Once jigdo-lite finishes scanning the files and
writing the temporary ISO file, it prints:

Copied input files to temporary file `woody-i386-1.iso.tmp'
- repeat command and supply more files to continue
-----------------------------------------------------------------
If you already have a previous version of the image you are
downloading, jigdo can re-use files on the old image that are also
present on the new image, and you do not need to download them
again. Mount the old CD ROM and enter the path it is mounted under
(e.g. `/mnt/cdrom'). Alternatively, just press enter if you want
to start the download of any remaining files.
You can also enter a single digit from the list below to
select the respective entry for scanning:
1: /mnt
Files to scan:

Since you normally don't have another source of files to scan other than your loop mounted
ISO file (or your CD), press ENTER. Jigdo-lite will then ask you about which
mirrors you want to use, just like it did when you downloaded your ISO for the first time. You've
already answered these questions before, but if you truly don't remember, you might want to
re-read Section 4.4.

At this point, you'll see jigdo-lite working its magic. Now
wasn't that easy?

6. Frequently Asked Questions

Questions prepended with a date indicate a time sensitive question (a question that relates
to a temporary situation). If you see one of these questions and know that the temporary
situation has changed, please contact me and let me know
so I can remove the question from the mini-HOWTO.

6.1. Why does jidgo ask twice for scanning for existing files? Is
it enough to say yes once ?

It keeps asking this as long as you enter a path to scan. The idea is that you may want
to scan several old CDs, so you can insert one after the other into the drive and keep
supplying the path "D:\" (or whatever). See also Section 7.2, "More About Scan Sources".

6.2. Jigdo Has Problems Downloading Certain Filenames.

When downloading Debian images under Windows, jigdo-lite may appear to have trouble
downloading one or more of the following files:

Move the jigdo download directory up by as many directories as possible, closer to the
drives's root directory.

The NTFS filesystem has a 255 character limit on a file's pathname. When jigdo-lite
downloads files from the internet, it makes a copy of the server directory structure in its
download directory. With their very long names, the above Debian packages may exceed the
allowed path length, which leads to error messages like "Cannot write to `[very long
pathname]' (No such file or directory)".

Some people may now wonder: Why does jigdo-lite use wget's
"--force-directories" switch, which creates these problematic directory
hierarchies?

Early versions of jigdo-lite did not use it, but then some folks requested that
jigdo-lite always use the "--continue" switch to avoid half-downloaded
.deb files being ignored and deleted when you interrupt and restart jigdo-lite.

Unfortunately, it turned out that this led to problems: The Debian servers contained
several identically named files (e.g. "root.bin") in different directories,
and if you interrupted jigdo-lite at roughly the right time during the download, the chances
were high that the resumed download would append data to the wrong half-downloaded file,
corrupting it and making the entire jigdo download fail.

6.3. How do I make jigdo use my proxy?

Edit ~/.jigdo-lite (or jigdo-lite-settings.txt
for the Microsoft Windows version) into a text editor and find the line that starts with
"wgetOpts". The following switches can be added to that line:

Of course, substitute the correct values for your proxy server. The last two options
are only necessary if your proxy uses password authentication. The switches need to be added
to the end of the wgetOpts line before the final ' character. All options
must be on one line.

Alternatively, under Linux you can also set up the ftp_proxy and
http_proxy environment variables, for example in the file
/etc/environment or ~/.bashrc.

6.4. Jigdo-lite fails with an error - have I downloaded all those MBs in vain?

If jigdo-file aborts after downloading a considerable chunk
of the ISO contents, you'll have a large ".iso.tmp" file. There are
several things to try to salvage your download:

Restart the download by pressing RETURN. Maybe some of the
files could not be downloaded because of timeouts or other transient errors. Try to download
the missing files again.

Try a different mirror. Some Debian mirrors are slightly out of sync -- maybe
a different mirror still holds files that were deleted from the one you specified, or it has
already been updated with files that are not yet present on your mirror. This has happened
quite a few times with me.

Retrieve the missing parts of the image using rsync. First, you need to find out the correct rsync URL
of the image you are downloading: Choose a server that offers rsync access to the stable or testing images, then determine the
correct path and filename. Directory listings can be obtained with commands like
rsync rsync://cdimage.debian.org/debian-cd/.

Next, remove the ".tmp" extension from jigdo-lite's temporary file
by renaming it, and pass both the remote URL and the local filename to rsync: rsync
rsync://server.org/path/binary-i386-1.iso binary-i386-1.iso You may want to use
rsync's --verbose and --progress switches to get
status messages, and --block-size=8192 to increase its
speed.

Under Linux, you can loop-mount the .tmp file to access the
packages that were already downloaded, and reuse them for generating an image from a newer
.jigdo file. To do this, first issue the following commands as root in the directory
with the broken download: mkdir mnt; mount -t iso9660 -o loop *.tmp mnt.
Next, start a new download in a different directory, and enter the path of the mnt directory
at the "Files to scan" prompt.

Under Microsoft Windows you can do the same thing by loop mounting the temporary ISO
image using "virtual drive" software. Daemon tools and Nero
Image Drive are both very popular. See also http://tinyurl.com/c39zr for more options.

6.5. [11 Aug 2002]: Why aren't the translations of this HOWTO on LDP?

I've been having trouble getting the translations of this HOWTO submitted to the
non-English LDP editors.

The German LDP editor, Marco Budde <Budde@tu-harburg.de> refuses to accept
the German translation because it was written in Docbook and not Linuxdoc, even though Docbook
is the preferred SGML language for the LDP. It's a shame that we have people within the open
source community who would sabotage our community from the inside.

If you care about having LDP documents in these languages, I urge you to write to these
editors and ask them to please be more responsible about accepting translated documents. For
the time being, you can download these translations from my personal website, http://www.dirac.org/linux/debian/jigdo.

6.6. What do I do if my jigdo download gets interrupted?

If your download gets interrupted, all you need to do is restart jigdo-lite and hit
ENTER at all the question prompts. Jigdo-lite will pick up where it left
off.

6.7. My jigdo download won't complete because the .jigdo file is broken. When I
download a new, fixed .jigdo file, do I need to download all the data over again?

You may find that the .jigdo file you downloaded is broken. It's uncommon, but it does
happen from time to time with moving targets like Debian testing or unstable.

If you find that .jigdo is broken, you'll need to download a new
.jigdo file (when a fixed one becomes available), but you won't need to
download all the ISO data again.

You can use the same loop mounting trick we use when updating an ISO image. The
difference is that there's no finished .iso file to start with, but the .iso.tmp file is an
ISO image too and can be used to finish the download without having to re-download all the
data that was downloaded before the broken .jigdo file caused jigdo-lite to halt. Simply loop
mount the .iso.tmp file on /mnt and when you re-run
jigdo-lite with the fixed .jigdo file, tell jigdo-lite to scan /mnt. Don't forget to rename or move the .iso.tmp file so it
doesn't interfere with jigdo-lite which will want to create a new .iso.tmp file.

6.8. Can I use jigdo to download images for DVD?

Absolutely; the process is identical to downloading CD images. The only thing you need
to do differently is to download the .jigdo and .template files for DVDs instead of CDs. You
can find the DVD .jigdo and .template files at http://www.debian.org/CD/jigdo-cd/.

On Linux, you need kernel 2.4 or later to create DVD-sized files.

Under MS Windows, you need to use jigdo-win-0.7.1a (released 21 July
2004) or later to create DVD-sized images. This is because of a bug in the large file support
of Mingw32, the compiler used to create the MS Windows executables. The bug got fixed on this
date, and jigdo-win-0.7.1a was released.

6.9. Can I burn the .iso.tmp file to CD?

Thanks to Gordon Huff and David Anselmi, we now know the answer is "yes you can". But
more importantly, Gordon gave a good reason why you'd want to do this in the first place.
Paraphrasing Gordon:

My friend's Win98 has a *nice* cable connection. I arrive in the morning, start jigdo
(more than one, actually) and then we go to the store, tie back the kiwi plant, put up the
Christmas lights and Christmas tree, trim the tree, order and split a pizza and fire up the
satellite dish.

I leave my friends place with several iso.tmp's on CDRWs. When I get home, I use the
iso's that didn't finish to update my jigdo setup at home which is a dial-up.

6.10. Jigdo-lite is broken! It downloads packages and deletes them. I know it doesn't write them to the
iso.tmp file because the file size doesn't change!

Jigdo works just fine -- the .iso.tmp file is created at the
beginning with its final size, but filled with zero bytes. Later, parts of it are overwritten
with the downloaded data.

You can tell that jigdo is making progress by looking at the messages "Found X
of the Y files required by the template" that are printed from time to time. The
first value "X" should increase. When X equals
Y, the download is finished.

6.11. I'm having trouble getting jigdo-easy to work.

6.12. For image updates, I want jigdo-lite to scan 14
loop-mounted images in one go. How can I do this?

When updating CD images, it's tiresome to keep loop-mounting and unmounting images.
However, by default the Linux kernel only supports eight loop devices, and jigdo-lite's menu
of previously entered paths only has five entries.

To scan many loop-mounted images, you must first tell the Linux kernel to support more
than the default eight devices. This is done by giving the "max_loop"
parameter to the module when loading it, e.g. with "modprobe loop
max_loop=16" on the command line or by adding the line "options loop
max_loop=16" to /etc/modules.conf. In Debian, you must put
this line into a file named e.g. /etc/modutils/local-loop and then run
update-modules because direct changes to
/etc/modules.conf will be overwritten.

Having mounted the individual images, you can pass the parent directory of their mount
points to jigdo-lite for scanning. For example, if the images are mounted under /mnt/myloopmounts/image1/ etc., pass "/mnt/myloopmounts" as the path to scan. If passing the parent
directory is inconvenient, you can also create a directory and fill it with symlinks to the
mount points.

6.13. Jigdo-lite is too verbose. How can I supress some or all of its messages?

Jigdo-lite uses wget, and wget's output can be quite verbose. If this is unsettling,
you can make wget more quiet by adding --non-verbose to the
wgetOpts switch in your ~/.jigdo-lite file. If you
want wget to print no messages at all, use --quiet in the
wgetOpts switch.

6.14. Can I use jigdo on platforms other than Linux?

Certainly. If you're interested in Potato or Woody under Microsoft Windows, old SunOS,
HP-UX and IRIX you can use jigdo-easy. See Section 7.1 and Section 7.4.

If you want to download Potato, Woody, Sarge or Sid under Microsoft Windows, jigdo-lite
has been ported to that platform and can be downloaded from the main jigdo site (Section 7.4).

6.15. On MS Windows, why do I get a "No such file or directory" error message?

You might find that under MS Windows, jigdo-lite will download some files but then fail
to read their contents, which will produce a "No such file or directory"
error message.

It seems that this occurs if the length of the filenames that jigdo processes exceeds a
certain limit. The solution is to move the half-finished download up in the directory
hierarchy, closer to the top-level directory of the drive.

6.16. On MS Windows, why won't my image grow larger than 2GB?

You're using an old version of jigdo. Please upgrade to
jigdo-win-0.7.1a or newer. See Section 6.8.

6.17. On MS Windows, jigdo-lite.bat fails with an error message
saying "sh" was not found.

This means that the PATH command in the .bat file failed. For some
reason, this is the case if you unpacked jigdo on a Windows network share using a path like
"\\SomeServer\Files\jigdo". Solution: Use "Map
network drive" (in the explorer "tools" menu) to assign a drive letter like
"Z:", then double-click on the .bat file inside
"Z:\jigdo". Alternatively, a workaround is to move
everything in the jigdo-bin subdirectory up to where the
.bat file is.

6.18. Can I run multiple instances of jigdo-lite to download images in parallel?

Absolutely. However, to avoid filename clashing, you should run each
jigdo-lite instance in its own separate directory. You can start
as many instances as you want, go to bed, and when you wake up, all the ISO images will be
waiting for you on your hard drive. Be aware that jigdo-lite is
bandwidth and CPU intensive, so you won't want to use your computer with multiple instances
running in tandem.

6.19. Is there a GUI interface available?

A GTK+ interface to jigdo is being worked on. Both Linux and Microsoft Windows GUI
clients are planned. Unfortunately, it's been 80% done for over 1.5 years, so don't hold your
breath for its release.

7. Errata

7.1. jigdo-easy

Jigdo-easy, by Anne Bezemer, is a fork of jigdo-lite which is
portable to a wider range of systems, including Microsoft Windows, old SunOS, HP-UX and IRIX).
It's also easier to use than jigdo-lite but because of changes made to Jigdo, will only work
with Potato and Woody. Jigdo-easy will not be able to download Sarge and Sid. See Section 7.4 and Section 6.14.

7.2. More About Scan Sources

By now you know that when jigdo-lite asks for files to scan,
you can use 3 sources:

A mounted copy of an outdated CD or DVD that you wish to
update.

A loop-mounted copy of an outdated ISO image file on your hard
drive.

A loop-mounted copy of the temporary .iso.tmp file,
when a previous jigdo-lite run aborted.

As Jens Seidel points out, there is another, rather crafty, source you should use for a
scanning source: your apt cache. Apt uses the directory /var/cache/apt/archives for cache. There will be many Debian
packages sitting in this directory, and they can be used for a scan source for
jigdo-lite! So when you're asked for a directory to scan, by all
means, use this directory too.

If you're editing the ~/.jigdo-lite file by hand, be aware that
multiple scan directories are space separated, for example:

scanMenu='/var/cache/apt/archives/ /cdrom/'

7.3. jigdo-file-cache.db

The cache contains the md5sums of files read when you supply a directory at the
Files to scan: prompt. If you have jigdo-file scan the same directory a
second time, the scan will be very fast.

This could be useful in the following case: rev0 gets updated to rev1. With the rev1 CD
images, some packages may have been pushed from CD n to CD
n+1, or vice versa. If you had a particularly slow link (e.g. modem),
you'd try to avoid downloading these packages again. For this reason, when downloading the
new version of CD n, you'd let jigdo-lite scan the three CDs
n-1, n and n+1 (or even all 8 CDs if
you want to be 100% sure).

If you have jigdo-lite scan the same CDs over and over again while updating each of the
8 CD images, the cache will prevent all the data on the CDs from being read multiple
times.

The cache is much more important when generating jigdo files,
because you don't want jigdo-file to read in your whole 50GB Debian mirror for every generated
jigdo file.

7.4. Resources

This HOWTO is winding down to a close, but I thought I'd leave you with a few links and
references to learn more about the jigdo tools and how they work.